Syringe Inspection Gets a Needed Dose of Automation

Dec. 1, 2015
Centralizing logic, motion, HMI and vision system data collection, PC-based control helped an inspection OEM reduce costs and streamline design for life sciences customers.

Spun off from custom packaging machinery manufacturer Luciano Packaging Technologies, Particle Inspection Technologies (PIT) specializes in particle and vision inspection systems for the pharmaceutical industry. Among its most recent developments is the PIL-30, which uses camera systems and software to inspect 30 filled and sealed syringes per minute, rejecting those with particle sizes outside predetermined FDA parameters.

At the heart of the sophisticated system is a single centralized controller with TwinCAT software from Beckhoff Automation. In addition to being able to run PLC functions, this PC-based platform also handles motion and HMI. And because it’s PC-based, it has a number of inherent communications benefits.

For example, the cameras in this application communicate with the TwinCAT software via standard Windows protocols. The USB3 connectivity between the cameras and the PC-based software is built right into the software. In this particular case, the TwinCAT control software is running on a standard non-industrial PC, which is perfectly suitable in the pharmaceutical environment, where everything is super clean and temperature-controlled.

PC-based control is especially helpful in a system where vision and cameras are involved, according to Doug Schuchart, regional sales manager for Beckhoff. “When capturing images and then analyzing them in order to make decisions on the machine control based upon what’s in those images, having a PC-based control platform offers huge advantages,” he says. “Combining the PC used for vision and the PLC into one centralized CPU provides significant cost savings. Plus, by having a large hard drive to store many large image files, the PIL-30 is able to quickly react, since the images are on the same PC as the machine control software—in this case, TwinCAT.”

Another key Beckhoff contribution to this machine is the EtherCAT industrial Ethernet system. The I/O system on the PIL-30 is networked via EK1100 EtherCAT couplers. Also from Beckhoff are the servo drives and motors that actuate the syringe inverter wheel, the main starwheel that takes syringes through all the inspection stations, two syringe-spinning stations, and finally a label application drum that rotates the syringes so that the pressure-sensitive labels can be smoothed out on the syringe body.

“I’ve been using Beckhoff controls for some time now,” says Jerry Wierciszewski, the PIT engineer principally responsible for the design of the machine. “The main reasons are flexibility, speed, and efficiency of communication.

Major leap forward

To appreciate the quantum leap forward this equipment represents, it’s important to realize that the customer that’s getting the equipment is currently doing particle inspection manually. To meet the inspection requirements dictated by the FDA, it takes 10-12 people working 20 hours/day. The PIL-30 will get the job done with two operators in an eight-hour shift.

When the machine is delivered, it will perform particle inspection in a semi-automatic mode. The two operators will sit in front of large-screen video monitors and watch a live feed of what the vision system is seeing enhanced in size 10 times. Because two people are looking for particles in every syringe, this amounts to 200 percent inspection.

In this semi-automatic mode, the inspectors will have to hit a touch pad to tell the Beckhoff controller that a syringe is good or has particles that call for rejection. The controller will signal the two reject stations whenever a syringe needs to be rejected.

The goal for the future is for this semi-automatic approach to become fully automated. Both the controller and the reject mechanisms are already fully capable of accomplishing what’s needed without any involvement from the two inspectors. But FDA validation will be necessary before the human inspectors can be eliminated. In a year or so, once enough data has been accumulated to document the machine’s performance, steps will likely be taken to validate the machine’s operation in a fully automated mode.

When running, the PIL-30 takes filled syringes through 11 different operating stations. Syringes enter the system on a gravity-fed track. A syringe is picked mechanically and placed in an intermittently rotating wheel that inverts it to a needle-up orientation. Once inverted, the syringe is pushed into one of 15 spring-loaded slots on an intermittently rotating star wheel that takes the syringes through all the various inspection stations that are part of the PIL-30. The machine deploys a total of seven Ximea cameras and a machine vision software system from Halcon.

Keeping it in motion

In Station 1, a servo motor spins the syringe relatively slowly so that all 360 degrees can be inspected for scratches. If there’s a scratch, the system automatically signals that syringe to be rejected. Once scratch inspection is complete, the syringe is spun at the much higher speed of 3,000 rpm to ensure that the liquid inside is moving. Then the syringe is advanced to Station 2.

The liquid needs to be in motion because the algorithm developed for particle inspection is based on image subtraction, Wierciszewski says. As soon as the spinning stops, the camera in Station 2 acquires about 50 images of the syringe, each captured 20 ms apart. The first of these images is the template against which all subsequent images are compared. If there’s a particle in the liquid, it will show up in a new position in the images taken after the template image because the liquid is moving, thanks to the spinner. When the system detects a difference between the template image and the subsequent images, it knows there is a particle in the liquid. If the particle is larger than what is deemed allowable, the system draws a circle around it when it appears on the video monitor. This alerts the operators to the existence of a particle so that they can use their touchpad to signal the controller that the syringe should be rejected.

Station 2 is for particle inspection against a white background, which makes dark particles visible. Station 3 is empty. Station 4 is similar to Station 1, where a spinner first rotates the syringe at a modest speed so that a camera can inspect for cracks. As with scratches, a cracked syringe is automatically targeted for rejection. Then the spinner goes into high-spin mode to again create movement of the liquid inside. The syringe is then advanced to Station 5 for particle inspection against a dark background, which makes particles that reflect light stand out. Again, if a particle shows up on the operator’s video monitor with a circle around it, the operator hits the touchpad to signal the system to reject that syringe.

Next is Station 6, a reject station that automatically ejects any syringe that has been identified by one of the two operators as faulty. Station 7 is empty, and Station 8 is occupied by a Herma H400 pressure-sensitive label applicator from Weber Labels & Labeling Systems. Integrated into the labeler is an X40 thermal-transfer printer from Markem-Imaje. Mounted to this station is an optical character recognition (OCR) camera from Halcon that verifies the variable information just printed by the thermal-transfer printer.

Station 9 is a busy one. The cap is inspected to make sure it’s neither too loose nor overtorqued. Also identified here is cap color so that, when syringes reach the discharge station, red-capped syringes can go down one discharge lane and blue down another. Station 9 also verifies the accuracy of label placement.

At Station 10, the syringe plunger is inspected to make sure there are no unwanted particulates on the plunger. Station 11 is a reject station. All that remains are Stations 12 and 13, for discharge of red and blue caps, respectively.

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